1. Field of the Invention
This invention relates generally to a boiler apparatus and specifically to a boiler apparatus utilizing dual gas pressure regulators with one regulator being a constant pressure gas regulator and the other regulator being a variable pressure gas regulator.
2. Description of the Related Art
In a direct fired steam generator, oxygen (air) and gas fuel are supplied to a burner chamber where the fuel is ignited. Water is likewise supplied to the burner chamber for conversion to steam. As opposed to a standard boiler mechanism wherein burnt combustion gases are exhausted through an output separate from the steam output, in a direct fired boiler, such burnt combustion gases are exhausted through the same output as the generated steam. Various direct fired boiler mechanisms are known in the prior art for producing the output of steam. These include U.S. Pat. Nos. 4,614,491; 5,368,474; 4,462,342; and 4,354,481 all issued to David P. Welden.
A common problem which exists in boilers of this type is the omission of carbon monoxide exhaust gases during the operation of the boiler. This problem occurs when the fuel/air mixture is too rich. A persistent problem in this field is the difficulty in designing a steam generator which can maintain a fuel/air mixture which is neither too lean nor too rich. This problem is particularly a concern when the steam generator is not operating at low pressures.
Gas pressure regulators can be used to help control the ratio. However, as the pressure in the burner chamber increases, the back pressure on the fuel line reduces the amount of fuel which is delivered to the burner. As a result the fuel/air mixture becomes too lean. Various variable gas pressure regulators have been used but these regulators are not without disadvantages. In practice, these regulators typically deliver a mixture which is too rich at the higher pressures and are exceedingly expensive.
Therefore, those concerned with these and other problems recognize the need for an improved system for delivering an appropriate fuel/air mixture to a burner chamber in a direct fired boiler system.